WARNING YOU MUST USE POWER BRAKE MASTER CYLINDERS

Original equipment power brake master cylinders for your car or truck will work fine.

Recommended bore size for master cylinder is 11/8 inch this gives plenty of volume for most systems.

Recommended master cylinder bore sizes 1.125 to 1.250 inch 1.125 working best with single piston calipers and 1.250 with multi piston 4 wheel disc brakes

People considering using a 1.25" bore MC to make sure they have enough volume is the wrong approach.

I am going to use your products on a Jeep with modified axles. The front brake calipers are off a Jeep Grand Wagoneer and the rears are front calipers off a Chevy Monte Carlo (single piston design smaller GM calipers). The Wagoneer came with a 1.125" MC from the factory so it makes sense that I would use a 1.125" bore MC with my hydrobooster.

If I was running one ton brakes or multi piston high performance calipers then I can see upgrading to 1.25" bore.

I have been told by several people that the best policy it to match the MC bore to the calipers and not get too much MC for the caliper. Just my 2 pennies worth of knowledge that adjusted for our current economy might be worth less than zero.

Because many people mix and match componits the only thing you can do is a recomendation.
I agree with your line of reasoning and would not use a 1.250 bore MC on a disc/drum system. 1.250 bore MC are not as common as 1.125 and it would be rare to need a 1.250 MC . So lets revise the statement 1.125 MC bore size covers most applications.
Disc/drum boosters put out less boost than a disc/disc booster so the 1.125 MC bore size works on both.
Just as a 1.250 MC bore would have little effect on a four wheel disc/disc multi piston preformance caliper and rotor.

Remember whole life must have balance Danial son.

Great input look forward to you posting more on the forum.